Photographic products and processes employing novel nondiffusible pyridylazonaphthol dye-releasing compounds

ABSTRACT

Photographic elements, diffusion transfer assemblages and processes are described which employ a novel nondiffusible compound having a releasable 2-(5-nitro-2-pyridylazo)-1-naphthol dye moiety. The compound contains a ballasted carrier moiety which is capable of releasing the diffusible azo dye under alkaline conditions. The dye is transferred imagewise to an image-receiving layer where it is contacted with metal ions to form a metal-complexed azo dye transfer image of excellent stability.

This is a division of application Ser. No. 832,499, filed Sept. 12, 1977.

This invention relates to photography and more particularly to color diffusion transfer photography employing certain nondiffusible azo dye-releasing compounds which, as a function of development of a silver halide emulsion layer, release a diffusible, metallizable 2-(5-nitro-2-pyridylazo)-1-naphthol dye. Highly stable metal complexes of this dye are formed in an image-receiving layer.

Azo dye developers containing metallizable groups are disclosed in U.S. Pat. Nos. 3,081,167; 3,196,014; 3,299,041; 3,453,107; and 3,563,739. Since it is a reactive species, however, the developer moiety of such dye developers is capable of developing any exposed silver halide emulsion layer that it comes into contact with, rather than just developing the adjacent silver halide emulsion with which it is associated. Unwanted wrong-layer development, therefore, can occur in dye developer systems which results in undesirable interimage effects. Accordingly, it is desirable to provide an improved transfer system in which the dyes is not attached to a "reactive" moiety, such as a developer moiety, so that such dye can diffuse throughout the photographic film unit without becoming immobilized in undesired areas.

In U.S. Published Patent Application No. B351,673, published Jan. 28, 1975, nondiffusible dye releasing compounds are disclosed. Among the various dye moieties disclosed which can be released are "metal complexed dyes". No specific structures are shown, however.

In U.S. Pat. Nos. 3,931,144; 3,932,380; 3,942,987; 3,954,476; 4,001,209; 4,013,633 and 4,013,635, various non-diffusible azo dye-releasing compounds are disclosed. The released dyes, however, are not disclosed as being metallized or metallizable.

The April 1977 edition of Research Disclosure, pages 32 through 39, discloses various nondiffusible dye-releasing compounds and various metallized azo dye fragments. Such premetallized dyes are large molecules which diffuse more slowly than unmetallized dyes, resulting in long access times for image formation. In any event, however, the specific compounds employed in the instant invention are not disclosed.

U.S. Pat. Nos. 3,086,005; 3,492,287 and 3,985,499 disclose various azo dyes, U.S. Pat. Nos. 2,348,417; 2,495,244; and 2,830,042 and French Pat. Nos. 1,124,882 and 1,200,358 disclose various azo dyes, U.S. Pat. Nos. 2,348,417; 2,495,244; and 2,830,042 and French Pat. Nos. 1,124,882 and 1,200,358 disclose various dyes from azopyridines, while U.S. Pat. Nos. 2,868,775; 2,938,895; 3,097,196; 3,691,161; and 3,875,139; British Pat. No. 899,758; and an article entitled "The Irgalan Dyes--Neutral-Dyeing Metal-Complex Dyes" by Guido Schetty, J. Soc. Dyers and Colourists, Volume 71, 1955, pages 705 through 724, disclose various metal complexed dyes. Again, however, neither the specific compounds employed in the instant invention nor the results obtained therewith are disclosed.

It would be desirable to provide improved dye-releasing compounds containing chelating dye moieties, so that the dye which is released imagewise during processing can diffuse to an image-receiving layer containing metal ions to form a metal-complexed, dye transfer image having better hues, rapid diffusion rates and shorter access times than those of the prior art, as well as good stability to heat, light and chemical reagents.

A photographic element in accordance with the invention comprises a support having thereon at least one photosensitive silver halide emulsion layer having associated therewith a nondiffusible compound having a releasable 2-(5-nitro-2-pyridylazo)-1-naphthol dye moiety, said compound containing a ballasted carrier moiety which is capable of releasing said diffusible azo dye under alkaline conditions, such as, for example, as a function (either direct or inverse) of development of the silver halide emulsion layer.

Good cyan dyes may be obtained in a preferred embodiment of the invention when the 2-(5-nitro-2-pyridylazo)-1-naphthol dye-releasing compound is represented by the formula: ##STR1## wherein:

G is a hydroxy group or a salt thereof (e.g., a sodium salt, a tetramethylammonium salt, etc,) or a hydrolyzable precursor thereof (e.g., an acyloxy group having the formula --OCOR¹, --OCOOR¹, or --OCON(R¹)₂, wherein each R¹ is an alkyl group having 1 to about 8 carbon atoms, such as methyl, ethyl, isopropyl, butyl and the like, or an aryl group having 6 to about 12 carbon atoms, such as phenyl, etc;) or a group which together with ##STR2## is CAR which is attached to the naphthalene group through the oxygen of the ##STR3## group;

R is an alkyl (including substituted alkyl) group of 1 to about 8 carbon atoms or CAR;

CAR represents said ballasted carrier moiety; and

t is 1 except when R is CAR or when G is a group which together with ##STR4## is CAR, in which case t is 0. When t is 0, preferably only one of R and G is CAR.

In a preferred embodiment of the invention, t is 0, R is CAR and G is OH. Other substituents may also be present in either of the two rings such as alkyl of 1 to 6 carbon atoms, alkoxy, halogens, solubilizing groups such as sulfonamido, sulfamoyl, carboxy, sulfo, hydrolyzable precursors thereof, etc.

When hydrolyzable precursors of the dye moiety of the above compounds are employed, the absorption spectrum of the azo dye is shifted to shorter wavelengths. "Shifted dyes" of this type absorb light outside the range to which the associated silver halide layer is sensitive. In some cases, the absorption spectrum of the unmetallized azo dye ligand is substantially shifted to shorter wavelengths at neutral pH (e.g., 5 to 8).

There is great latitude in selecting a CAR moiety which is attached to the 2-(5-nitro-2-pyridylazo)-1-naphthol dye-releasing compounds described above. Depending upon the nature of the ballasted carrier selected, various groups may be needed to attach or link the carrier moiety to the dye. Such linking groups are considered to be a part of the CAR moiety in the above definition. It should also be noted that when the dye moiety is released from the compound, cleavage may take place in such a position that part or all of a linking group if one is present, and even part of the ballasted moiety may be transferred to the image-receiving layer along with the dye moiety. In any event, the dye nucleus as shown above can be thought of as the "minimum" which is transferred.

CAR moieties useful in the invention are described in U.S. Pat. Nos. 3,227,550; 3,628,952; 3,227,552; and 3,844,785 (dye released by chromogenic coupling); U.S. Pat. Nos. 3,443,939 and 3,443,940 (dye released by intramolecular ring closure); U.S. Pat. Nos. 3,698,897 and 3,725,062 (dye released from hydroquinone derivatives); U.S. Pat. No. 3,728,113 (dye released from a hydroquinonylmethyl quaternary salt); U.S. Pat. Nos. 3,719,489 and 3,443,941 (silver ion induced dye release); and U.S. Pat. Nos. 3,245,789 and 3,980,497; Canadian Pat. No. 602,607; British Pat. No. 1,464,104; Research Disclosure 14447, April 1976; and commonly assigned copending U.S. Application Ser. No. 775,025, filed Mar. 7, 1977 of Chasman et al (dye released by miscellaneous mechanisms), the disclosures of which are hereby incorporated by reference.

In a further preferred embodiment of the invention, the ballasted carrier moiety of CAR as described above may be represented by the following formula:

    (Ballast-Carrier-Link)--

wherein:

(a) Ballast is an organic ballasting radical of such molecular size and configuration as to render the compound nondiffusible in a photographic element during development in an alkaline processing composition;

(b) Carrier is an oxidizable acyclic, carbocyclic or heterocyclic moiety (see "The Theory of the Photographic Process", by C. E. K. Mees and T. H. James, Third Edition, 1966, pages 282 to 283), e.g., moieties containing atoms according to the following configuration:

    a (--C═C).sub.b --

wherein:

b is a positive integer of 1 to 2; and

a represents the radicals OH, SH, NH--, or hydrolyzable precursors thereof; and

(c) Link represents a group which upon oxidation of said Carrier moiety is capable of being hydrolytically cleaved to release the diffusible azo dye. For example, Link may be the following groups: ##STR5## wherein * represents the position of attachment to Carrier.

The Ballast group in the above formula is not critical as long as it confers nondiffusibility to the compound. Typical Ballast groups include long-chain alkyl radicals linked directly or indirectly to the compound as well as aromatic radicals of the benzene and naphthalene series indirectly attached or fused directly to the ring, etc. Useful Ballast groups generally have at least 8 carbon atoms such as substituted or unsubstituted alkyl groups of 8 to 22 carbon atoms, a carbamoyl radical having 8 to 30 carbon atoms such as --CONH(CH₂)₄ --O--C₆ H₃ (C₅ H₁₁)₂, --CON(C₁₂ H₂₅)₂, etc, a keto radical having 8 to 30 carbon atoms such as --CO--C₁₇ H₃₅, --CO--C₆ H₄ (t--C₁₂ H₂₅), etc.

For specific examples of Ballast-Carrier-Link moieties useful as the CAR moiety in this invention, reference is made to the November 1976 edition of Research Disclosure, pages 68 through 74, and the April 1977 edition of Research Disclosure, pages 32 through 39, the disclosures of which are hereby incorporated by reference.

In a highly preferred embodiment of the invention, the ballasted carrier moiety or CAR in the above formulas is a group having the formula: ##STR6## wherein:

(a) Ballast is an organic ballasting radical of such molecular size and configuration (e.g., simple organic groups or polymeric groups) as to render the compound nondiffusible in a photographic element during development in an alkaline processing composition;

(b) D is OR² or NHR³ wherein R² is hydrogen or a hydrolyzable moiety and R³ is hydrogen or a substituted or unsubstituted alkyl group of 1 to 22 carbon atoms such as methyl, ethyl, hydroxyethyl, propyl, butyl, secondary butyl, tert-butyl, cyclopropyl, 4-chlorobutyl, cyclobutyl, 4-nitro-amyl, hexyl, cyclohexyl, octyl, decyl, octadecyl, dodecyl, benzyl, phenethyl, etc. (when R³ is an alkyl group of greater than 8 carbon atoms, it can serve as a partial or sole Ballast);

(c) Y represents the atoms necessary to complete a benzene nucleus, a naphthalene nucleus, or a 5 to 7 membered heterocyclic ring such as pyrazolone, pyrimidine, etc;

(d) j is a positive integer of 1 to 2 and is 2 when D is OR² or when R³ is hydrogen or an alkyl group of less than 8 carbon atoms; and

(e) L is a linking group which is [X--(NR⁴ --J)_(q) ]_(m) -- or X--J--NR⁴ -- wherein:

(i) X represents a bivalent linking group of the formula --R⁵ --L'_(n) --R⁵ _(p) -- where each R⁵ can be the same or different and each represents an alkylene radical having 1 to about 8 carbon atoms, such as methylene, hexylene and the like; a phenylene radical; or a substituted phenylene radical having 6 to about 9 carbon atoms, such as methoxy phenylene;

(ii) L' represents a bivalent radical selected from oxy, imino, carbonyl, carboxamido, carbomoyl, sulfonamido, ureylene, sulfamoyl, sulfinyl or sulfonyl;

(iii) n is an integer of 0 or 1;

(iv) p is 1 when n equals 1 and p is 1 or 0 when n equals 0, provided that when p is 1 the carbon content of the sum of both R⁵ radicals does not exceed 14 carbon atoms;

(v) R⁴ represents a hydrogen atom, or an alkyl radical having 1 to about 6 carbon atoms;

(vi) J represents a bivalent radical selected from sulfonyl or carbonyl;

(vii) q represents an integer of 0 or 1; and

(viii) m represents an integer of 0, 1 or 2.

Especially good results are obtained in the above formula when D is OH, j is 2, Y is a naphthalene nucleus, G is OH, t is 0 and R is CAR.

Examples of the CAR moiety in this highly preferred embodiment are disclosed in U.S. Published Patent Application No. B351,673; U.S. Pat. No. 3,928,312; French Pat. No. 2,284,140; and German Pat. Nos. 2,406,664; 2,613,005; and 2,505,248, the disclosures of which are hereby incorporated by reference, and include the following: ##STR7##

In another highly preferred embodiment of the invention, the ballasted carrier moiety or CAR in the above formulas is such that the diffusible azo dye is released as an inverse function of development of the silver halide emulsion layer under alkaline conditions. This is ordinarily referred to as positive-working dye-release chemistry. In one of these embodiments, the ballasted carrier moiety or CAR in the above formulas may be a group having the formula: ##STR8## wherein:

Ballast is an organic ballasting radical of such molecular size and configuration as to render the compound nondiffusible in a photographic element during development in an alkaline processing composition;

W² represents at least the atoms necessary to complete a benzene nucleus (including various substituents thereon); and

R⁷ is an alkyl (including substituted alkyl) radical having 1 to about 4 carbon atoms.

Examples of the CAR moiety in this formula I include the following: ##STR9##

In a second embodiment of positive-working dye-release chemistry as referred to above, the ballasted carrier moiety or CAR in the above formulas may be a group having the formula: ##STR10## wherein:

Ballast is an organic ballasting radical of such molecular size and configuration as to render the compound nondiffusible in a photographic element during development in an alkaline processing composition;

W¹ represents at least the atoms necessary to complete a quinone nucleus (including various substituents thereon);

r is a positive integer of 1 or 2;

R⁶ is an alkyl (including substituted alkyl) radical having 1 to about 40 carbon atoms or an aryl (including substituted aryl) radical having 6 to about 40 carbon atoms; and

k is a positive integer of 1 to 2 and is 2 when R⁶ is a radical of less than 8 carbon atoms.

Examples of the CAR moiety in this formula II include the following: ##STR11##

In using the compounds in formulas I and II above, they are employed in a photographic element similar to the other nondiffusible dye-releasers described previously. Upon reduction of the compound as a function of silver halide development under alkaline conditions, the metallizable azo dye is released. In this embodiment, conventional negative-working silver halide emulsions, as well as direct-positive emulsions, can be employed. For further details concerning these particular CAR moieties, including synthesis details, reference is made to commonly assigned copending U.S. Application Ser. No. 775,025 of Chasman et al, filed Mar. 7, 1977, the disclosure of which is hereby incorporated by reference.

In a third embodiment of positive-working dye-release chemistry as referred to above, the ballasted carrier moiety or CAR in the above formulas may be a group having the formula: ##STR12## wherein:

Ballast, W² and R⁷ are as defined for formula I above.

Examples of the CAR moiety in this formula III include the following: ##STR13##

For further details concerning this particular CAR moiety, including synthesis details, reference is made to commonly assigned copending U.S. Application Ser. No. 534,966 of Hinshaw et al, filed Dec. 20, 1974, the disclosure of which is hereby incorporated by reference.

In a fourth embodiment of positive-working dye-release chemistry as referred to above, the ballasted carrier moiety or CAR in the above formulas may be a group having the formula: ##STR14## wherein:

Ballast, r, R⁶ and k are as defined for formula II above;

W² is as defined for formula I above; and

K is OH or a hydrolyzable precursor thereof.

Examples of the CAR moiety in this formula IV include the following: ##STR15##

For further details concerning this particular CAR moiety, including synthesis details, reference is made to U.S. Pat. No. 3,980,479 of Fields et al, issued Sept. 14, 1976, the disclosure of which is hereby incorporated by reference.

A bivalent linking group, e.g., L or X as defined above, may be used, if desired, to link the CAR moiety described in formulas I through IV above to the dye moiety previously described.

Representative compounds included within the scope of the invention include the following: ##STR16##

A process for producing a photographic transfer image in color according to the invention comprises:

(a) treating an imagewise-exposed photographic element as described above with an alkaline processing composition in the presence of a silver halide developing agent to effect development of each of the exposed silver halide emulsion layers,

(b) the dye-releasing compound then releasing the diffusible azo dye as described above imagewise as a function of the development of each of the silver halide emulsion layers;

(c) at least a portion of the imagewise distribution of the azo dye diffusing to a dye image-receiving layer; and

(d) contacting the imagewise distribution of azo dye with metal ions, thereby forming a metal-complexed azo dye transfer image.

In another preferred embodiment of the invention, a process for producing a photographic transfer image in color according to the invention comprises:

(a) treating an imagewise-exposed photographic element as described above wherein CAR in the compound has the formula: ##STR17## D, Y, L and j being defined as above, with an alkaline processing composition in the presence of a silver halide developing agent to effect development of each of the exposed silver halide emulsion layers, thereby oxidizing the developing agent;

(b) the oxidized developing agent thereby cross-oxidizing the dye-releasing compound;

(c) the cross-oxidized dye-releasing compound then cleaving as a result of alkaline hydrolysis to release the diffusible azo dye imagewise as a function of the imagewise exposure of each of the silver halide emulsion layers;

(d) at least a portion of the imagewise distribution of the azo dye diffusing to a dye image-receiving layer; and

(e) contacting the imagewise distribution of azo dye with metal ions, thereby forming a metal-complexed azo dye transfer image.

The tridentate azo dye ligand which is released from the dye-releasing compounds in accordance with the present invention will form a coordination complex in the image-receiving layer with polyvalent metal ions. The metal ions can be present in the image-receiving layer itself or in a layer adjacent thereto or the image-receiving layer can be contacted with metal ions in a bath after diffusion of the dye has taken place. Metal ions most useful in the invention are those which are essentially colorless when incorporated into the image-receiving element, are inert with respect to the silver halide layers, react readily with the released dye to form a complex of the desired hue, are tightly coordinated to the dye in the complex, have a stable oxidation state, and form a dye complex which is stable to heat, light and chemical reagents. In general, good results are obtained with polyvalent metal ions such as copper (II), zinc (II), nickel (II), platinum (II), palladium (II) and cobalt (II) ions.

For example, it is believed that the coordination complex which is formed from the tridentate azo dye ligand according to the invention in one of the preferred embodiments thereof has the following structure: ##STR18## where R⁸ is an alkyl (including substituted alkyl) group of 1 to about 8 carbon atoms, Me is metal and Lig is one or more ligand groups depending upon the coordination number of the metal ion, such as H₂ O, Cl, pyridine, etc.

Thus, in accordance with another embodiment of the invention, a photographic element is provided which comprises a support having thereon a coordination complex of a polyvalent metal ion and a compound having the formula: ##STR19## wherein R⁸ is as described above. The element usually contains a photographic mordant or image-receiving layer to bind the dye or coordination complex thereto. The structures shown above may also, of course, be substituted in the same manner as described above for the starting compounds from which they are released, e.g., the pyridine ring may be substituted in the 3-position with a methyl group, etc.

It will be appreciated that, after processing the photographic element described above, there remains in it after transfer has taken place an imagewise distribution of azo dye in addition to developed silver. A color image comprising residual nondiffusible compound may be obtained in this element if the residual silver and silver halide are removed by any conventional manner well known to those skilled in the photographic art, such as a bleach bath followed by a fix bath, a bleach-fix bath, etc. Such a retained dye image should normally be treated with metal ions to metallize the dyes to increase their light fastness and shift their spectral absorption to the intended region. The imagewise distribution of azo dye may also diffuse out of the element into these baths, if desired, rather than to an image-receiving element. If a negative-working silver halide emulsion is employed in certain preferred photosensitive elements, described above, then a positive color image, such as a reflection print, a color transparency or motion picture film, may be produced in this manner. If a direct-positive silver halide emulsion is employed in such photosensitive elements, then a negative color image may be produced.

The photographic element in the above-described process can be treated with an alkaline processing composition to effect or initiate development in any manner. A preferred method for applying processing composition is by use of a rupturable container or pod which contains the composition. In general, the processing composition employed in this invention contains the developing agent for development, although the composition could also just be an alkaline solution where the developer is incorporated in the photographic element, image-receiving element or process sheet, in which case the alkaline solution serves to activate the incorporated developer.

A photographic film unit which can be processed in accordance with this invention is adapted to be processed by passing the unit between a pair of juxtaposed pressure-applying members, such as would be found in a camera designed for in-camera processing, and comprises:

(1) a photographic element as described above;

(2) a dye image-receiving layer; and

(3) means for discharging an alkaline processing composition within the film unit, such as a rupturable container which is adapted to be positioned during processing of the film unit so that a compressive force applied to the container by the pressure-applying members will effect a discharge of the container's contents within the film unit;

the film unit containing a silver halide developing agent.

In the embodiment described above, the dye image-receiving layer may itself contain metal ions or the metal ions may be present in an adjacent layer, so that the tridentate azo dye ligand which is released will form a coordination complex therewith. The dye thus becomes immobilized in the dye image-receiving layer and metallized at the same time. Alternatively, the dye image in the dye image-receiving layer may be treated with a solution containing metal ions to effect metallization. The formation of the coordination complex shifts the absorption of the dye to the desired hue, usually to longer wavelengths, which have a different absorption than that of the initial dye-releasing compound. If this shift is large enough, then the dye-releasing compound may be incorporated in a silver halide emulsion layer without adversely affecting its sensitivity.

The dye image-receiving layer in the above-described film unit can be located on a separate support adapted to be superposed on the photographic element after exposure thereof. Such image-receiving elements are generally disclosed, for example, in U.S. Pat. No. 3,362,819. When the means for discharging the processing composition is a rupturable container, it is usually positioned in relation to the photographic element and the image-receiving element so that a compressive force applied to the container by pressure-applying members, such as would be found in a typical camera used for in-camera processing, will effect a discharge of the container's contents between the image-receiving element and the outermost layer of the photographic element. After processing, the dye image-receiving element is separated from the photographic element.

The dye image-receiving layer in the above-described film unit can also be located integral with the photographic element between the support and the lowermost photosensitive silver halide emulsion layer. One useful format for integral receiver-negative photographic elements is disclosed in Belgian Pat. No. 757,960. In such an embodiment, the support for the photographic element is transparent and is coated with an image-receiving layer, a substantially opaque light-reflective layer, e.g., TiO₂, and then the photosensitive layer or layers described above. After exposure of the photographic element, a rupturable container containing an alkaline processing composition and an opaque process sheet are brought into superposed position. Pressure-applying members in the camera rupture the container and spread processing composition over the photographic element as the film unit is withdrawn from the camera. The processing composition develops each exposed silver halide emulsion layer and dye images are formed as a function of development which diffuse to the image-receiving layer to provide a positive, right-reading image which is viewed through the transparent support on the opaque reflecting layer background. For other details concerning the format of this particular integral film unit, reference is made to the above-mentioned Belgian Pat. No. 757,960.

Another format for integral negative-receiver photographic elements in which the present invention can be employed is disclosed in Belgian Pat. No. 757,959. In this embodiment, the support for the photographic element is transparent and is coated with the image-receiving layer, a substantially opaque, light-reflective layer and the photosensitive layer or layers described above. A rupturable container containing an alkaline processing composition and an opacifier is positioned adjacent the top layer and a transparent top sheet which has thereon a neutralizing layer and a timing layer. The film unit is placed in a camera, exposed through the transparent top sheet and then passed through a pair of pressure-applying members in the camera as it is being removed therefrom. The pressure-applying members rupture the container and spread processing composition and opacifier over the negative portion of the film unit to render it light-insensitive. The processing composition develops each silver halide layer and dye images are formed as a result of development which diffuse to the image-receiving layer to provide a positive, right-reading image which is viewed through the transparent support on the opaque reflecting layer background. For further details concerning the format of this particular integral film unit, reference is made to the above-mentioned Belgian Pat. No. 757,959.

Still other useful integral formats in which this invention can be employed are described in U.S. Pat. Nos. 3,415,644; 3,415,645; 3,415,646; 3,647,437; and 3,635,707. In most of these formats, a photosensitive silver halide emulsion is coated on an opaque support and a dye image-receiving layer is located on a separate transparent support superposed over the layer outermost from the opaque support. In addition, this transparent support also preferably contains a neutralizing layer and a timing layer underneath the dye image-receiving layer.

Another embodiment of the invention uses the image-reversing technique disclosed in British Pat. No. 904,364, page 19, lines 1 through 41. In this process, the dye-releasing compounds are used in combination with physical development nuclei in a nuclei layer contiguous to the photosensitive silver halide negative emulsion layer. The film unit contains a silver halide solvent, preferably in a rupturable container with the alkaline processing composition.

The film unit or assembly used in the present invention may be used to produce positive images in single- or multicolors. In a three-color system, each silver halide emulsion layer of the film assembly will have associated therewith a dye-releasing compound which releases a dye possessing a predominant spectral absorption within the region of the visible spectrum to which said silver halide emulsion is sensitive (initially or after forming the coordination complex), i.e., the blue-sensitive silver halide emulsion layer will have a yellow or yellow-forming dye-releaser associated therewith, the green-sensitive silver halide emulsion layer will have a magenta or magenta-forming dye-releaser associated therewith, and the red-sensitive silver halide emulsion layer will have a cyan or cyan-forming dye-releaser associated therewith, at least one of the dye-releasers being a compound in accordance with the present invention. The dye-releaser associated with each silver halide emulsion layer may be contained either in the silver halide emulsion layer itself or in a layer contiguous to the silver halide emulsion layer.

The concentration of the dye-releasing compounds that are employed in the present invention may be varied over a wide range, depending upon the particular compound employed and the results which are desired. For example, the dye-releasers of the present invention may be coated in layers by using coating solutions containing between about 0.5 and about 8 percent by weight of the dye-releaser distributed in a hydrophilic film-forming natural material or synthetic polymer, such as gelatin, polyvinyl alcohol, etc, which is adapted to be permeated by aqueous alkaline processing composition.

Depending upon which CAR is used in the present invention, a variety of silver halide developing agents can be employed. In certain embodiments of the invention, any silver halide developing agent can be employed as long as it cross-oxidizes with the dye-releasers described herein. The developer may be employed in the photosensitive element to be activated by the alkaline processing composition. Specific examples of developers which can be employed in this invention include:

N-methylaminophenol

Phenidone (1-phenyl-3-pyrazolidone

Dimezone (1-phenyl-4,4-dimethyl-3-pyrazolidone) aminophenols

1-phenyl-4-methyl-4-hydroxymethyl-3-pyrazolidone

N,n-diethyl-p-phenylenediamine

N,n,n',n'-tetramethyl-p-phenylenediamine

3-methyl-N,N-diethyl-p-phenylenediamine

3-methoxy-N-ethyl-N-ethoxy-p-phenylenediamine, etc.

The non-chromogenic developers in this list are preferred, however, since they avoid any propensity of staining the dye image-receiving layer.

In a preferred embodiment of the invention, the silver halide developer employed in the process becomes oxidized upon development and reduces silver halide to silver metal. The oxidized developer then cross-oxidizes the dye-releasing compound. The product of cross-oxidation then undergoes alkaline hydrolysis, thus releasing an imagewise distribution of diffusible azo dye which then diffuses to the receiving layer to provide the dye image. The diffusible moiety is transferable in alkaline processing composition either by virtue of its self-diffusivity or by its having attached to it one or more solubilizing groups, for example, a carboxy, sulpho, sulphonamido, hydroxy or morpholino group.

In using the dye-releasing compounds according to the invention which produce diffusible dye images as a function of development, either conventional negative-working or direct-positive silver halide emulsions may be employed. If the silver halide emulsion employed is a direct-positive silver halide emulsion, such as an internal-image emulsion designed for use in the internal image reversal process or a fogged, direct-positive emulsion such as a solarizing emulsion, which is developable in unexposed areas, a positive image can be obtained in certain embodiments on the dye image-receiving layer. After exposure of the film unit, the alkaline processing composition permeates the various layers to initiate development of the exposed photosensitive silver halide emulsion layers. The developing agent present in the film unit develops each of the silver halide emulsion layers in the unexposed areas (since the silver halide emulsions are direct-positive ones), thus causing the developing agent to become oxidized imagewise corresponding to the unexposed areas of the direct-positive silver halide emulsion layers. The oxidized developing agent then cross-oxidizes the dye-releasing compounds and the oxidized form of the compounds then undergoes a base-catalyzed reaction to release the dyes imagewise as a function of the imagewise exposure of each of the silver halide emulsion layers. At least a portion of the imagewise distributions of diffusible dyes diffuse to the image-receiving layer to form a positive image of the original subject. After being contacted by the alkaline processing composition, a pH-lowering layer in the film unit or image-receiving unit lowers the pH of the film unit or image receiver to stabilize the image.

Internal-image silver halide emulsions useful in this invention are described more fully in the November 1976 edition of Research Disclosure, pages 76 through 79, the disclosure of which is hereby incorporated by reference.

The various silver halide emulsion layers of a color film assembly employed in this invention can be disposed in the usual order, i.e., the blue-sensitive silver halide emulsion layer first with respect to the exposure side, followed by the green-sensitive and red-sensitive silver halide emulsion layers. If desired, a yellow dye layer or a yellow colloidal silver layer can be present between the blue-sensitive and green-sensitive silver halide emulsion layers for absorbing or filtering blue radiation that may be transmitted through the blue-sensitive layer. If desired, the selectively sensitized silver halide emulsion layers can be disposed in a different order, e.g., the blue-sensitive layer first with respect to the exposure side, followed by the red-sensitive and green-sensitive layers.

The rupturable container employed in certain embodiments of this invention can be of the type disclosed in U.S. Pat. Nos. 2,543,181; 2,643,886; 2,653,732; 2,723,051; 3,056,492; 3,056,491 and 3,152,515. In general, such containers comprise a rectangular sheet of fluid- and air-impervious material folded longitudinally upon itself to form two walls which are sealed to one another along their longitudinal and end margins to form a cavity in which processing solution is contained.

Generally speaking, except where noted otherwise, the silver halide emulsion layers employed in the invention comprise photosensitive silver halide dispersed in gelatin and are about 0.6 to 6 microns in thickness; the dye-releasers are dispersed in an aqueous alkaline solution-permeable polymeric binder, such as gelatin, as a separate layer about 0.2 to 7 microns in thickness; and the alkaline solution-permeable polymeric interlayers, e.g., gelatin, are about 0.2 to 5 microns in thickness. Of course, these thicknesses are approximate only and can be modified according to the product desired.

Scavengers for oxidized developing agent can be employed in various interlayers of the photographic elements of the invention. Suitable materials are disclosed on page 83 of the November 1976 edition of Research Disclosure, the disclosure of which is hereby incorporated by reference.

Any material can be employed as the image-receiving layer in this invention as long as the desired function of mordanting or otherwise fixing the dye images is obtained. The particular material chosen will, of course, depend upon the dye to be mordanted. Suitable materials are disclosed on pages 80 through 82 of the November 1976 edition of Research Disclosure, the disclosure of which is hereby incorporated by reference.

Use of a pH-lowering material in the film units employed in this invention will usually increase the stability of the transferred image. Generally, the pH-lowering material will effect a reduction in the pH of the image layer from about 13 or 14 to at least 11 and preferably 5 to 8 within a short time after imbibition. Suitable materials and their functioning are disclosed on pages 22 and 23 of the July 1974 edition of Research Disclosure and pages 35 through 37 of the July 1975 edition of Research Disclosure, the disclosures of which are hereby incorporated by reference.

A timing or inert spacer layer can be employed in the practice of this invention over the pH-lowering layer which "times" or controls the pH reduction as a function of the rate at which alkali diffuses through the inert spacer layer. Examples of such timing layers and their functioning are disclosed in the Research Disclosure articles mentioned in the paragraph above concerning pH-lowering layers.

The alkaline processing composition employed in this invention is the conventional aqueous solution of an alkaline material, e.g., alkali metal hydroxides or carbonates such as sodium hydroxide, sodium carbonate or an amine such as diethylamine, preferably processing a pH in excess of 11, and preferably containing a developing agent as described previously. Suitable materials and addenda frequently added to such compositions are disclosed on pages 79 and 80 of the November 1976 edition of Research Disclosure, the disclosure of which is hereby incorporated by reference.

While the alkaline processing composition used in this invention can be employed in a rupturable container, as described previously, to conveniently facilitate the introduction of processing composition into the film unit, other methods of inserting processing composition into the film unit could also be employed, e.g., interjecting processing solution with communicating members similar to hypodermic syringes which are attached either to a camera or camera cartridge. The processing composition may also be applied by means of a swab or by dipping in a bath, if so desired.

The alkaline solution-permeable, substantially opaque, light-reflective layer employed in certain embodiments of photographic film units used in this invention are described more fully in the November 1976 edition of Research Disclosure, page 82, the disclosure of which is hereby incorporated by reference.

The supports for the photographic elements used in this invention can be any material as long as it does not deleteriously affect the photographic properties of the film unit and is dimensionally stable. Typical flexible sheet materials are described on page 85 of the November 1976 edition of Research Disclosure, the disclosure of which is hereby incorporated by reference.

While the invention has been described with reference to layers of silver halide emulsions and dye image-providing materials, dotwise coating, such as would be obtained using a gravure printing technique, could also be employed. In this technique, small dots of blue-, green- and red-sensitive emulsions have associated therewith, respectively, dots of yellow, magenta and cyan color-providing substances. After development, the transferred dyes would tend to fuse together into a continuous tone.

The silver halide emulsions useful in this invention, both negative-working and direct-positive ones, are well known to those skilled in the art and are described in Product Licensing Index, Volume 92, December 1971, publication 9232, page 107, paragraph I, "Emulsion types"; they may be chemically and spectrally sensitized as described on page 107, paragraph III, "Chemical sensitization", and pages 108 and 109, paragraph XV, "Spectral sensitization", of the above article; they can be protected against the production of fog and can be stabilized against loss of sensitivity during keeping by employing the materials described on page 107, paragraph V, "Antifoggants and stabilizers", of the above article; they can contain development modifiers, hardeners, and coating aids as described on pages 107 and 108, paragraph IV, "Development modifiers"; paragraph VII, "Hardeners"; and paragraph XII, "Coating aids", of the above article; they and other layers in the photographic elements used in this invention can contain plasticizers, vehicles and filter dyes described on page 108, paragraph XI, "Plasticizers and lubricants", and paragraph VIII, "Vehicles", and page 109, paragraph XVI, "Absorbing and filter dyes", of the above article; they and other layers in the photographic elements used in this invention may contain addenda which are incorporated by using the procedures described on page 109, paragraph XVII, "Methods of addition", of the above article; and they can be coated by using the various techniques described on page 109, paragraph XVIII, "Coating procedures", of the above article, the disclosures of which are hereby incorporated by reference.

The term "nondiffusing" used herein has the meaning commonly applied to the term in photography and denotes materials that for all practical purposes do not migrate or wander through organic colloid layers, such as gelatin, in the photographic elements of the invention in an alkaline medium and preferably when processed in a medium having a pH of 11 or greater. The same meaning is to be attached to the term "immobile". The term "diffusible" as applied to the materials of this invention has the converse meaning and denotes materials having the property of diffusing effectively through the colloid layers of the photographic elements in an alkaline medium in the presence of "nondiffusing" materials. "Mobile" has the same meaning.

The term "associated therewith" as used herein is intended to mean that the materials can be in either the same or different layers so long as the materials are accessible to one another.

EXAMPLE 1 Preparation of Compound 1

4-(1-Carboxyethoxy)-2-(5-nitro-2-pyridylazo)-1-naphthol (22.9 g--0.06 mol) and 4-(3-aminopropanesulfonamido)-N-[4-(2,4-di-t-pentylphenoxy)butyl]-1-hydroxy-2-naphthamide hydrochloride (38.9 g--0.06 mol) were suspended in 400 ml dimethylformamide (DMF) and cooled to 0° C. A solution of diphenylphosphoryl azide (C₂ H₅ O)₂ P(O)N₃ (16.7 g--0.061 mol), dissolved in 100 ml DMF was added slowly over 20 minutes. Triethylamine (13.1 g--0.13 mol) was then added over 30 minutes and the mixture stirred overnight, the temperature rising to room temperature. After filtering off some insoluble residue, the solution was diluted with 300 ml of water. The precipitated solid was filtered off, washed and dried. The solid was dissolved in chloroform and chromatographed on a column of silica gel yielding about 23 g of red solid which was recrystallized from 30 ml DMF. The solution was poured into 400 ml boiling methanol and chilled. The yield was 13.3 g (23 percent), m.p. 139° to 142° C.

Intermediates 2-Hydrazino-5-nitropyridine.

To a slurry of 47.6 g (0.3 mol) of 2-chloro-5-nitropyridine in a mixture of 400 ml methanol and 60 ml water and cooled to 10° C. was added with cooling below 30° 86 g hydrazine (95 percent) over about 10 minutes. The solids first went into solution, then a greenish-yellow precipitate separated. The mixture was stirred at reflux for 30 minutes. The greenish solid was filtered off and washed with cold methanol. The solid was slurried in 200 ml of cold water, washed and vacuum dried. The yield was 40.1 g (87 percent).

4-(1-Carboxyethoxy)-1,2-naphthoquinone.

To a solution of 38.0 g potassium dihydrogen phosphate in 7.5 l of distilled water (pH 4.0) was added 89.4 g (0.33 mol) potassium nitrosodisulfonate (Fremy's reagent). To this solution was added immediately a solution of 34.8 g (0.15 mol) of 2-(4-hydroxy-1-naphthoxy)propionic acid in 125 ml ethanol. The mixture was stirred for 2.5 hours under nitrogen at room temperature. The yellow-brown solid was collected, washed with a little water and dried (under nitrogen). The yield was 30.0 g (81 percent). The crude product melted at 182 to 184° C.

4-(1-Carboxyethoxy)-2-(5-nitro-2-pyridylazo)-1-naphthol.

The above hydrazinonitropyridine (17.0 g, 0.11 mol) was dissolved in 200 ml of water containing 17 ml concentrated hydrochloric acid. This solution was added over one-half hour at room temperature to a solution of the above 1,2-naphthoquinone (27.1 g, 0.11 mol) in 1 liter of acetic acid. The mixture, after stirring for 4 hours at room temperature, was filtered, yielding a red solid. It was slurried in 400 ml of water, then filtered off and dried overnight. The yield was 29.7 g (70 percent). It was recrystallized from hot methanol.

EXAMPLE 2 Photographic Test

A single-color integral-imaging receiver element was prepared by coating successively on a polyester film support (1) a metallizing layer comprising gelatin (1.08 g/m²) and nickel sulfate hexahydrate (0.58 g/m²), (2) a receiving layer comprising a mixture of gelatin and poly(4-vinylpyridine), (each at 2.15 g/m²), (3) a reflecting layer comprising titanium dioxide and gelatin in a 6.25/1 ratio, (4) an opaque layer of carbon dispersed in gelatin, (5) a layer comprising gelatin and a dispersion of Compound 1 (0.84 g/m²), (6) a layer of a green-sensitized internal image emulsion as described in Evans, U.S. Pat. No. 3,761,276 (2.69 g/m² Ag, 2.69 g/m² gelatin), with fogging agents NA-16 and H-25 of Leone et al, U.S. Pat. No. 4,030,925, issued June 21, 1977, and 5-octadecylhydraquinone-2-sulfonic acid (16 g/mole Ag), (7) a layer of didodecylhydroquinone (1.29 g/m²) dispersed in gelatin (1.61 g/m²), and (8) a gelatin overcoat layer. In a comparative coating in which no metal ion is used to chelate the dye, the entire layer 1 was omitted. Layers 1 and 2 above form no part of the invention, as they are the subject of an invention by our coworkers Brust, Hamilton and Wilkes.

This integral element was exposed to a multicolor test object, then processed by spreading between it and a processing cover sheet, as described in U.S. Pat. No. 4,061,496 of Hannie et al issued Dec. 6, 1977 at 22° C., a viscous processing composition, as described in said U.S. Pat. No. 4,061,496, filed Apr. 14, 1976, of Hannie et al, by passing the transfer "sandwich" between a pair of juxtaposed rollers so that the liquid layer was about 75 μm. The dye reflection density in the unexposed areas (i.e., D_(max) areas) was measured with a recording spectrophotometer. From the spectrophotometric curves, the final D_(max), the λ_(max) (i.e., wavelength at D_(max)) and "half band width" (1/2 BW) were determined and recorded in Table I. The "half band width" is the wavelength range at half the D_(max), a measure of purity of hue: The narrower the 1/2 BW, the purer the hue. The light stability was determined by exposing part of the strip to a high intensity daylight (5000 footcandles) light source for two days. Values are given for the original density D_(o), the final faded density D_(F), and the density loss .increment.D. D_(max) and D_(min) values from the sensitometric test pattern were also obtained.

                  TABLE I                                                          ______________________________________                                                 Hue                                                                            λ.sub.max                                                                      1/2 BW  Light Stability                                         D.sub.max                                                                             D.sub.min                                                                             (nm)     (nm)  D.sub.o                                                                               D.sub.F                                                                             ΔD                              ______________________________________                                         1.84   0.22   642      133   1.00   0.97 -0.03                                 ______________________________________                                    

EXAMPLE 3 Released Dye

A series of model dyes or released dyes (i.e., not attached to a ballasted carrier) having the following formula: ##STR20## were each dissolved in an alkaline solution having the final composition: Dye 2.5×10⁻³ M, sodium hydroxide 0.5M and hydroxyethylcellulose 30 g/l. It was spread in a thin layer between a cover sheet of polyester film support and a receiving element which consists of a polyester film support and a layer containing a mordant mixture of gelatin (2.2 g/m²) and a latex, poly(styrene-co-N-benzyl-N,N-dimethyl-N-vinylbenzylammonium sulfate-co-divinylbenzene), (2.2 g/m²). When the dye is adsorbed to the mordant, the sheets are peeled apart and the dyed sheet is washed and dried.

For metallizing the dyes with nickel(II) ions, two procedures were used: (A) the above receiving element was modified to include bis(acetylacetonato)nickel(II) (0.65 g/m²) in the mordant layer, and (B) a receiving element was prepared comprising a polyester support on which was coated Layers 1 and 2 of the element of Example 2.

For metallizing the dyes with copper(II) ions, a sample of the dyed receiving element was treated for five minutes with a solution 0.5M in cupric ion: 6.0 g cupric nitrate (.3H₂ O), 75 g tartaric acid, 91 ml of 0.5M aqueous dipotassium hydrogen phosphate, 109 ml 1.5M aqueous potassium dihydrogen phosphate, sodium hydroxide to adjust the pH to 6.0, all per liter of solution.

After metallizing, the strips were washed, soaked in a phosphate buffer to adjust the pH to 7.0, then washed again and dried.

Hue: The wavelength at the maximum density (λ_(max)) of the spectrophotometric curves is recorded in Table II along with the "half band width" (1/2BW).

Light Stability: The above dye receiving elements were subjected to 21 days of a simulated average northern skylight (SANS) (500 footcandles) fading test. The loss in density (.increment.D) was monitored spectrophotometrically and is set forth in Table II.

Under the conditions of the Experiments, the hue and light stability of the dyes were highly dependent on the presence of and specific selection of the metal ion. Nickel (II) ion produced highly stable images with a bright cyan hue and narrow absorption bands.

                                      TABLE II                                     __________________________________________________________________________                             Hue         Light                                      Compound                λ.sub.max                                                                  1/2 BW   Stability                                  Number                                                                               R.sup.8                                                                           R.sup.9        (nm)                                                                              (nm)                                                                               Me.sup.++                                                                           D.sub.o                                                                           ΔD                                __________________________________________________________________________     12    Cl OH             648                                                                               165 None (H)                                                                            2.50                                                                              -0.92                                                           655                                                                               125 Cu   2.35                                                                              -0.91                                                           671                                                                               126 Ni-(A)                                                                              2.24                                                                              -0.30                                   13    CH.sub.3                                                                          OH             658                                                                               122 Cu   1.37                                                                              -0.43                                                           673                                                                               112 Ni-(A)                                                                              1.47                                                                              -0.37                                   14    H  OH             642                                                                               136 Cu   1.43                                                                              -0.45                                   15    H  NH.sub.m C.sub.6 H.sub.4OH                                                                    644                                                                               --  Ni-(B)                                                                              1.50                                                                              -0.14                                   16    H  NH(CH.sub.2).sub.3 SO.sub.2 NH.sub.2                                                          656                                                                               --  Ni-(B)                                                                              1.28                                                                              0                                                               641                                                                               --  Cu   0.89                                                                              -0.13                                   17    H  NH.sub.m C.sub.6 H.sub.4SO.sub.2 NH.sub.2                                                     640                                                                               --  Ni-(B)                                                                              0.84                                                                              -0.10                                                           632                                                                               --  Cu   1.06                                                                              -0.30                                   18    H                                                                                  ##STR21##     646 636                                                                           -- --                                                                              Ni-(B) Cu                                                                           1.44 1.12                                                                         -0.19 -0.35                             19    CH.sub.3                                                                          NH(CH.sub.2).sub.3 SO.sub.2 NH.sub.2                                                          664                                                                               --  Ni-(B)                                                                              1.48                                                                              -0.09                                                           653                                                                               --  Cu   0.80                                                                              -0.09                                   __________________________________________________________________________

The invention has been described in detail with particular reference to preferred embodiments thereof, but it will be understood that variations and modifications can be effected within the spirit and scope of the invention. 

What is claimed is:
 1. A nondiffusible compound having a releasable 4-alkoxy-2-(5-nitro-2-pyridylazo)-1-naphthol dye moiety, said compound containing a ballasted carrier moiety which is capable of releasing said diffusible azo dye under alkaline conditions, the alkyl of said alkoxy group being an alkyl or substituted alkyl group of 1 to about 8 carbon atoms.
 2. The compound of claim 1 which has the formula: ##STR22## wherein: G is a hydroxy group, a salt thereof, or a hydrolyzable precursor thereof; or a group which together with ##STR23## is CAR, said CAR being attached to the naphthalene group through the oxygen of said ##STR24## group; R is an alkyl or substituted alkyl group of 1 to about 8 carbon atoms or CAR;Car represents said ballasted carrier moiety; and t is 1, except when R is CAR or when G is a group which together with ##STR25## is CAR, in which case t is
 0. 3. The compound of claim 2 wherein t is 0, R is CAR and G is OH.
 4. The compound of claim 2 wherein G is hydroxy; or an acyloxy group having the formula --OCOR¹, --OCOOR¹, or --OCON(R¹)₂, wherein R¹ is an alkyl group having 1 to about 8 carbon atoms or an aryl group having 6 to about 12 carbon atoms; or a group which together with ##STR26## is CAR, said CAR group being attached to the naphthalene group through the oxygen of said ##STR27## group.
 5. The compound of claim 2 wherein said CAR is a group having the formula:

    (Ballast-Carrier-Link)--

wherein: (a) Ballast is an organic ballasting radical of such molecular size and configuration as to render said compound nondiffusible in a photographic element during development in an alkaline processing composition; (b) Carrier is an oxidiable acyclic, carbocyclic or heterocyclic moiety; and (c) Link represents a group which upon oxidation of said carrier moiety is capable of being hydrolytically cleaved to release said diffusible azo dye.
 6. The compound of claim 5 wherein the Carrier moiety contains atoms according to the following configuration:

    a (--C═C).sub.b --

wherein: b is a positive integer of 1 to 2; and a represents the radicals OH, SH, NH--, or hydrolyzable precursors thereof.
 7. The compound of claim 2 wherein said CAR is a group having the formula: ##STR28## wherein: (a) Ballast is an organic ballasting radical of such molecular size and configuration as to render said compound nondiffusible in a photographic element during development in an alkaline processing composition;(b) D is OR² or NHR³ wherein R² is hydrogen or a hydrolyzable moiety and R³ is hydrogen or a substituted or unsubstituted alkyl group of 1 to 22 carbon atoms; (c) Y represents the atoms necessary to complete a benzene nucleus, a naphthalene nucleus, or a 5 to 7 membered heterocyclic ring; (d) j is a positive integer of 1 to 2 and is 2 when D is OR² or when R³ is hydrogen or an alkyl group of less than 8 carbon atoms; and (e) L is a linking group which is [X--(NR⁴ --J)_(q) ]_(m) -- or X--J--NR⁴ -- wherein:(i) X represents a bivalent linking group of the formula --R⁵ --L'_(n) --R⁵ _(p) -- where each R⁵ can be the same or different and each represents an alkylene radical having 1 to about 8 carbon atoms; a phenylene radical; or a substituted phenylene radical having 6 to about 9 carbon atoms; (ii) L' represents a bivalent radical selected from oxy, carbonyl, carboxamido, carbamoyl, sulfonamido, ureylene, sulfamoyl, sulfinyl or sulfonyl; (iii) n is an integer of 0 or 1; (iv) p is 1 when n equals 1 and p is 1 or 0 when n equals 0, provided that when p is 1 the carbon content of the sum of both R⁵ radicals does not exceed 14 carbon atoms; (v) R⁴ represents a hydrogen atom, or an alkyl radical having 1 to about 6 carbon atoms; (vi) J represents a bivalent radical selected from sulfonyl or carbonyl; (vii) q represents an integer of 0 or 1; and (viii) m represents an integer of 0, 1 and
 2. 8. The compound of claim 7 wherein D is OH, j is 2, Y is a naphthalene nucleus, G is OH, t is 0 and R is CAR.
 9. The compound of claim 2 wherein said CAR is capable of releasing said diffusible azo dye as an inverse function of development of a silver halide emulsion layer under alkaline conditions.
 10. The compound of claim 9 wherein said CAR is a group having the formula: ##STR29## wherein: Ballast is an organic ballasting radical of such molecular size and configuration as to render said compound nondiffusible in a photographic element during said development in an alkaline processing composition;W¹ represents at least the atoms necessary to complete a quinone nucleus; r is a positive integer of 1 or 2; R⁶ is an alkyl radical having 1 to about 40 carbon atoms or an aryl radical having 6 to about 40 carbon atoms; and k is a positive integer of 1 to 2 and is 2 when R⁶ is a radical of less than 8 carbon atoms.
 11. The compound of claim 9 wherein said CAR is a group having the formula: ##STR30## wherein: Ballast is an organic ballasting radical of such molecular size and configuration as to render said compound nondiffusible in a photographic element during said development in an alkaline processing composition;W² represents at least the atoms necessary to complete a benzene nucleus; and R⁷ is an alkyl radical having 1 to about 4 carbon atoms.
 12. The compound of claim 9 wherein said CAR is a group having the formula: ##STR31## wherein: Ballast is an organic ballasting radical of such molecular size and configuration as to render said compound nondiffusible in a photographic element during said development in an alkaline processing composition;W² represents at least the atoms necessary to complete a benzene nucleus; and R⁷ is an alkyl radical having 1 to about 4 carbon atoms.
 13. The compound of claim 9 wherein said CAR is a group having the formula: ##STR32## wherein: Ballast is an organic ballasting radical of such molecular size and configuration as to render said compound nondiffusible in a photographic element during said development in an alkaline processing composition;W² represents at least the atoms necessary to complete a benzene nucleus; r is a positive integer of 1 or 2; R⁶ is an alkyl radical having 1 to about 40 carbon atoms or an aryl radical having 6 to about 40 carbon atoms; k is a positive integer of 1 to 2 and is 2 when R⁶ is a radical of less than 8 carbon atoms; and K is OH or a hydrolyzable precursor thereof.
 14. The compound of claim 1 which has the formula: ##STR33##
 15. The compound of claim 1 which has the formula: ##STR34##
 16. A coordination complex of a polyvalent metal ion and a compound having the following formula: ##STR35## wherein: R⁸ is an alkyl or substituted alkyl group of 1 to about 8 carbon atoms.
 17. The complex of claim 16 wherein the metal ion is nickel (II), copper (II), zinc (II), platinum (II), palladium (II) or cobalt (II).
 18. A photographic element comprising a support having thereon a coordination complex of a polyvalent metal ion and a compound having the following formula: ##STR36## wherein: R⁸ is an alkyl or substituted alkyl group of 1 to about 8 carbon atoms.
 19. The photographic element of claim 18 wherein the metal ion is nickel (II), copper (II), zinc (II), platinum (II), palladium (II) or cobalt (II). 